The catalytic oxidation of 2,3,5-trimethylphenol was carried out with aqueous hydrogen peroxide over spinel CuCO2O4; under the mild conditions, this study realized 80% selectivity for 2,3,5-trimethylquinone at 100% conversion of 2,3,5-trimethylphenol. The catalyst was investigated by XRD, TEM, UV-vis and FT-IR; and the reaction has been studied by different parameters like performance of different catalysts, effect of aqueous hydrogen peroxide, reaction time, reaction temperature, solvents, catalyst concentration, catalyst separation, and recycling of catalyst. Compared to the conventional methods. this method could be more eco-friendly. (c) 2006 Elsevier B.V. All rights reserved.